Furnaces employed for melting and holding non-ferrous metals, such as aluminum and alloys thereof, typically have employed heating chambers with a relatively large vertical dimension above the surface of the metal bath. Heating elements, usually gas burners, have been positioned in the side walls of the furnaces well above the surface of the metal bath being heated. U.S. Pat. Nos. 2,020,101 and 2,264,740 to Brown are examples of the typical arrangement.
A continuing problem in the art is to more efficiently transfer heat from the heating element to the metal bath, thereby to reduce energy requirements for operation of a furnace. As indicated in U.S. Pat. No. 2,331,887 to Bonsack, in melting and holding furnaces for light metals, non-ferrous metals and alloys thereof, it has been recognized to be undesirable to permit the products of combustion and the flame from the burners to come into direct contact with the surface of the metal bath. In attempts to provide a required heat and efficiency, conduit structures, disposed adjacent the metal bath, have been proposed which isolate the flame and combustion products from the bath.
Another continuing problem in the art, as pointed out in U.S. Pat. No. 3,735,968 to Pearch, is reduction of wear on the metal bath container due to unevent heating of the container resulting in hot spots. Heater bank structures, disposed adjacent the exterior of the container side walls and the combustion gases from which are sealed off from the metal bath, have been proposed.